During the surgical removal of a tumor, the problem arises that healthy tissue frequently cannot be distinguished with the naked eye from a tissue affected by a tumor. In order to provide a remedy here, the patient is administered before the operation with a fluorescent dye that is specifically enriched in the tumor. During the operation, the exposed tissue is illuminated with a light in the near infrared region that is suitable for exciting the fluorescent dye. The tissue is recorded with the aid of an image acquisition device that has an optical unit for separating a fluorescent image generated by the fluorescent light, and a native tissue image formed by the ambient light. The recorded fluorescent images and the tissue images are superimposed by means of an image processing device, the tumorous tissue being labeled in the superimposed image by means, for example, of a false color display.
Arranged downstream of an objective in the conventional image acquisition device is a beam splitter that distributes the recorded image over two different channels that are each provided with a camera. One channel is used to record the fluorescent image, and the other channel is used to record the native tissue image. The conventional image acquisition device requires a relatively high outlay on production because, in particular, of the provision of a beam splitter.